Key legal question
Whether the appellants met the conditions for voluntary AHV/IV accession, in particular the five-year prior compulsory insurance requirement.
Extracted holding
The record was incomplete on the decisive question whether the appellants remained domiciled in Switzerland until 2005; the case had to be sent back for fresh fact-finding and a new decision.
Extracted reasoning
The lower court relied only on population-register data, which is merely an indication of domicile and does not conclusively establish a civil-law domicile change. Because domicile under Art. 1a AHVG depends on civil-law domicile principles, the relevant facts had to be examined ex officio.